将我的用户保存到CoreData似乎正在保存，因为do catch保存块不会引发任何错误，实际上我确实获得了成功打印，但是在加载已保存的用户时找不到。 我注意到了这一点，因为当我启动该应用程序时，每次登录时都会从firebase下载用户。 基本上，整个逻辑是：

登录调用User.findUser()，它将在CoreData中寻找用户 如果找到，它将仅加载用户详细信息并继续，否则将调用Firebase.downloadUserDetails()，它将在Firebase中寻找用户（在这种情况下，这是用户首次在设备上启动应用程序）。如果找到，它将下载用户的详细信息并调用User.saveUserDetails()，将用户保存到CoreData。因此，在下次登录时应该找到它。好吧，如果我在此之后重新运行应用程序，User.findUser()仍然找不到任何用户，然后重新启动整个过程。

我以前没有意识到这一点，因为User.saveUserDetails()在保存时不显示任何错误，但是我在CoreData中添加了对任何User记录的检查，并且始终显示0

您能看到发生了什么吗？如何检查是否在AppDelegate中正确设置了CoreData？

这是保存功能：

static func saveUserDetails(completed: @escaping(Bool) -> (),userId: String,fcmToken: String,email: String,fullName: String,familyName: String,givenName: String,profileImage: UIImage,address: String,city: String,zipCode: String,region: String,country: String,phoneNumber: String) {

        let context = AppDelegate.viewContext
        //check if user is already in database
        let request: NSFetchRequest<User> = User.fetchRequest()

        // check for any existing records in CoreData
        print("check for any existing records in CoreData")
        do {
            let fetchPre = try context.fetch(request)
            print("saveUserDetails: Users saved in CoreData are: \(fetchPre.count)")

            for user in fetchPre {
                print("User id is : \(String(describing: user.userId))")
                print("User name is : \(String(describing: user.fullName))")
            }
        } catch  {
            print(" Error fetching user during saving : \(error)")
        }


        request.predicate = NSPredicate(format: "userId == %@",userId)
        //        request.fetchLimit = 1
        do {
            let fetch = try context.fetch(request)
            print("saveUserDetails: fetch is \(fetch.count)")
            for value in fetch {
                print(" User/saveUserDetails:   checking for existing user")
                if userId == value.userId {
                    print("   user is already saved ")
                    // save changes in database
//                    value.setvalue(userId,forKey: "userId")
                    value.setvalue(fcmToken,forKey: "fcmToken")
                    value.setvalue(fullName,forKey: "fullName")
                    value.setvalue(familyName,forKey: "familyName")
                    value.setvalue(givenName,forKey: "givenName")
                    value.setvalue(address,forKey: "address")
                    value.setvalue(city,forKey: "city")
                    value.setvalue(region,forKey: "region")
                    value.setvalue(zipCode,forKey: "zipCode")
                    value.setvalue(country,forKey: "country")
                    value.setvalue(phoneNumber,forKey: "phoneNumber")
                    value.setvalue(email,forKey: "email")
                    //                    return
                } else {
                    print(" User/saveUserDetails: user is new")
                    //create user in database
                    let user = User(context: context)
                    user.userId = userId
                    user.fcmToken = fcmToken
                    user.fullName = fullName
                    user.familyName = familyName
                    user.givenName = givenName
                    user.address = address
                    user.zipCode = zipCode
                    user.city = city
                    user.region = region
                    user.country = country
                    user.phoneNumber = phoneNumber
                    user.profilePicture = uiimagejpegrepresentation(profileImage,1.0)! as NSData

                }

                do {
                    // save changes in database
                    try context.save()
                    print("  User/saveUserDetails: user is saved")
                    completed(true)
                } catch  {
                    print("Error saving user details : \(error)")
                }
            }
        } catch  {
            print(" Error fetching user during saving : \(error)")

        }

    }